I don't like the DeviantArt critique system, but I will give some feedback. The foreground looks really nice - quite detailed. The figures and objects are well drawn.
The lighting looks off. I can't quite tell where the light source is. I can tell that the characters are sitting under trees in the shade. Light falls on the beach, but then seems to dissipate too quickly on the water. If there were more reflections on the water, then there I could see from which direction the sun is shining.
The objects in the distance are too detailed, especially the water. Less lines and more solid color - same thing with the sky at the horizon line. You would want to do the same things with the rocks. They look very close to the subjects in the picture. If you want them to seem father away then they need less detail. You can smudge the colors together for a more blurred effect rather than the strokes.
Hope any of this is helpful. I like your picture and think you can make some great improvements to it!